{
  "id": "days-until-april-9",
  "version": "7c26677f4d2c",
  "status": "published",
  "name": "Days Until April 9",
  "question": "Days until April 9",
  "summary": "Counts the days from today, or any date you choose, to the next April 9, with its day of the week.",
  "category": "days",
  "subcategory": "countdowns",
  "url": "https://www.acalculator.org/days/days-until-april-9",
  "markdown": "https://www.acalculator.org/days/days-until-april-9.md",
  "kind": "function",
  "method": "Find the first April 9 on or after the start date, then count the days from the start date to it.",
  "assumptions": [
    "April 9 comes every year, so the count is never more than 365 days.",
    "The start date itself is not counted: from the day before April 9, the count is 1; on April 9 itself, it is 0.",
    "Start dates from January 1, 1900 to December 31, 2400 work for the count to April 9, the range the date field accepts.",
    "Today is the date on your own device, so the count to April 9 changes at midnight where you are. Dates are whole calendar days, so a daylight-saving change never adds or loses a day."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "from": {
        "title": "Count from",
        "description": "The date to count from. Today, unless you change it.",
        "type": "string",
        "format": "date"
      }
    }
  },
  "outputs": {
    "days": {
      "label": "Days until April 9",
      "description": "Whole days from the start date to the next April 9; 0 on the day itself.",
      "format": "integer"
    },
    "date": {
      "label": "Date",
      "description": "The next April 9 on or after the start date.",
      "format": "date-long"
    },
    "weekday": {
      "label": "Day of the week",
      "description": "The weekday of that date.",
      "format": "text"
    },
    "weeks": {
      "label": "In weeks",
      "description": "The same number of days in weeks and days.",
      "format": "text"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "from": "2026-09-30"
    },
    "outputs": {
      "days": 191,
      "date": "2027-04-09",
      "weekday": "Friday",
      "weeks": "27 weeks and 2 days"
    },
    "text": "From September 30, 2026, there are 191 days until April 9 on Friday, April 9, 2027."
  },
  "examples": [
    {
      "given": {
        "from": "2027-04-09"
      },
      "expect": {
        "date": "2027-04-09",
        "days": 0
      },
      "source": "U.S. Naval Observatory, Leap Years: the Gregorian leap year rule (https://aa.usno.navy.mil/faq/leap_years); Python 3 datetime (docs/progress/WP-44/truth.py)"
    },
    {
      "given": {
        "from": "2027-01-01"
      },
      "expect": {
        "date": "2027-04-09",
        "days": 98
      },
      "source": "U.S. Naval Observatory, Leap Years: the Gregorian leap year rule (https://aa.usno.navy.mil/faq/leap_years); Python 3 datetime (docs/progress/WP-44/truth.py)"
    },
    {
      "given": {
        "from": "2027-04-10"
      },
      "expect": {
        "date": "2028-04-09",
        "days": 365
      },
      "source": "U.S. Naval Observatory, Leap Years: the Gregorian leap year rule (https://aa.usno.navy.mil/faq/leap_years); Python 3 datetime (docs/progress/WP-44/truth.py)"
    }
  ],
  "sources": [
    "5 U.S.C. 6103 (federal holidays; weekend rule in 6103(b) and Executive Order 11582). Checked against OPM holiday schedules.",
    "Equinoxes and solstices: Jean Meeus, Astronomical Algorithms (2nd ed., 1998), chapter 27, checked against the US Naval Observatory."
  ],
  "related": [
    "days-until-april-8",
    "days-until-april-10",
    "days-until-april-1",
    "days-until-april-2",
    "days-until-april-3",
    "days-until-april-4",
    "days-until-april-5",
    "days-until-april-6",
    "days-until-april-7",
    "days-until-april-11",
    "days-until-april-12",
    "days-until-april-13",
    "days-until-april-14",
    "days-until-april-15",
    "days-until-april-16",
    "days-until-april-17",
    "days-until-april-18",
    "days-until-april-19",
    "days-until-april-20",
    "days-until-april-21",
    "days-until-april-22",
    "days-until-april-23",
    "days-until-april-24",
    "days-until-april-25",
    "days-until-april-26",
    "days-until-april-27",
    "days-until-april-28",
    "days-until-april-29",
    "days-until-april-30",
    "days-between-dates"
  ],
  "changelog": []
}